Advertise the new cache structure in a news file

sbidoul · sbidoul · commit 600778a4eaba · 2019-11-18T14:45:50.000+01:00
diff --git a/news/7296.removal b/news/7296.removal
@@ -0,0 +1,3 @@
+The pip>=20 wheel cache is not retro-compatible with previous versions. Until
+version 21, pip will still be able to take advantage of existing legacy cache
+entries.

Original file line number	Diff line number	Diff line change
`@@ -0,0 +1,3 @@`
	`1`	`+The pip>=20 wheel cache is not retro-compatible with previous versions. Until`
	`2`	`+version 21, pip will still be able to take advantage of existing legacy cache`
	`3`	`+entries.`